Teach Him to Kiss
If it doesn't help, then really examine what you don't like about his kiss. Is it too much tongue? Not enough? Too much spit? Loose lips? It's important not to bruise the old ego when you approach your sweetie about his pucker, so begin the conversation with what you do like about his kiss. "I think it's sexy when you press a little harder as we kiss." - that sort of sentiment will point him in the right direction and protect his feelings. But if it's not working, then don't be afraid to be direct but gentle. Perhaps if you demonstrate how you like to be kissed on him, then have him try the same way of kissing on you, then he'll get the point. Before you even have the conversation, however, be sure that disliking the way he kisses isn't symptomatic of a bigger problem, like disliking him altogether. It's easy to find fault in the little things when you're unhappy.